Fuel delivery system

ABSTRACT

A fuel delivery system and fuel injector is disclosed. The fuel delivery system includes a bore ( 18 ) which is formed in the head ( 10 ) of the engine and a fuel injector ( 21 ) is located in the bore ( 18 ). The bore ( 18 ) has an open end. The heating chamber ( 40 ) is defined between the fuel injector and the wall ( 18   a ) of the bore ( 18 ). The injector has a fuel storage section which is located within the heating chamber and during a compression stroke of the piston of the engine, gas in the combustion chamber of the engine is compressed and forced through the open end of the bore into the chamber to heat the fuel storage section of the injector. In an alternative arrangement, the injector is provided with an enlarged end region ( 110 ) which fits into the bore of the engine and makes contact with the peripheral wall of the bore so that heat is conducted from the engine via the peripheral wall of the bore into the enlarged section of the injector to heat the fuel within the end region of the injector.

FIELD OF THE INVENTION

This invention relates to a fuel delivery system and, in particular, toa direct injection fuel delivery system for both diesel and petrol orgasoline engines, and also to an injector and fuel delivery system forsuch systems.

BACKGROUND OF THE INVENTION

Our International Application No. PCT/AU02/00403 discloses a fueldelivery system in which fuel is injected into an air intake stream inorder for the fuel to be delivered to a combustion chamber of theengine. The contents of this International application are incorporatedinto this specification by this reference.

In diesel engines and in direct injection petrol engines, fuel isdelivered direct to the combustion chamber or a secondary chamberdirectly linked to the combustion chamber (herein collectively referredto as the combustion chamber) rather than into the air intake stream.

SUMMARY OF THE INVENTION

The object of one aspect of the present invention is to provide a fueldelivery system which utilises the principles of the above Internationalapplication, but which is applicable to a direct injection engine.

This aspect of the invention may be said to reside in a fuel deliverysystem for an engine which has a combustion chamber, a piston moveablein the combustion chamber, an air inlet port and an exhaust port,comprising:

a bore in the engine having a first open end communicating with thecombustion chamber, and a second end remote from the first end, the borehaving a bore wall;

a fuel injector located in the bore and having an injection tip adjacentthe first end for direct injection of fuel into the combustion chamber,the injector having a fuel storage section in which fuel is stored forejection from the injector and an operating section for operating theinjector to eject the fuel from the tip of the injector;

the second end of the bore being closed;

a heating chamber defined by the bore wall, the closed second end of thebore and the injector;

the injector being located in the bore so that the fuel storage sectionis within the heating chamber; and

wherein during a compression stroke of the piston gas within thecombustion chamber is compressed and forced through the first open endof the bore into the chamber to heat the fuel storage section of theinjector so as to raise the temperature of the fuel in the fuel storagesection so that as soon as the fuel leaves the injector, the fuelsubstantially immediately converts to vapour state because of theheating of the fuel and the change in pressure experienced by the fuelwhen the fuel leaves the injector and enters the chamber.

Thus, according to this aspect of the invention, the fuel is heated bythe compression of the gases within the cylinder during the compressionstrokes of the piston. In the case of a diesel engine in which theengine operates at very high compression ratio, the heating is greaterbecause of the higher compression pressure within the engine, therebyenabling the rather thicker diesel fuel to be adequately heated toensure that it converts to vapour upon ejection from the injector. Inthe case of a petrol or gasoline engine which operates at a lowerpressure, the heating is not as great, but nevertheless sufficient toheat the temperature to cause the petrol or gasoline to rise to therequired temperature in order to immediately convert to vapour uponinjection of the fuel. Thus, the required heating is to some extentautomatically regulated depending on the type of engine (ie. whether itbe a diesel engine or spark ignited petrol engine) and the fuel which isbeing used. The invention also has the advantage that additional heatingelements are not required and additional plumbing or significantmodifications to the engine are also not required.

The operating section of the injector may be a mechanical operatingsection which is operated by fuel pressure, or an electric solenoid typeoperating section, to thereby enable the fuel to be ejected at therequired time by the injector.

In the case of a mechanical operating section, it is preferred that theinjector be located in the bore so that the mechanical operating sectionis exterior of the heating chamber. However, this is not essential. Inthe case of an electric operating section, the electric operatingsection should be exterior of the chamber to prevent the heating withinthe chamber from destroying the electric operating section of theinjector. In other words, by locating the electric operating sectionoutside the chamber, it is maintained relatively cool, thereby notdamaging the electric components within the operating section.

In the preferred embodiment of the invention, the bore has an inwardlydirected flange and a collar located on the flange for receiving an endof the injector so as to raise the injector slightly in the bore and toprovide a passage through which the gases compressed in the cylinder canpass into the heating chamber.

Preferably the second end of the bore is closed by a sealing element.

The sealing element may be an O-ring type seal, a plate or any otherelement for sealing the second end of the bore to prevent gases withinthe combustion chamber from exiting the bore through the second end.

In one embodiment, the sealing element is a shoulder formed on theinjector remote from the tip for sealing the second end of the bore.

The collar may be a generally annular ring and may include apertures orholes to facilitate the passage of gas from the combustion chamber intothe heating chamber, and from the heating chamber back into thecombustion chamber.

Another aspect of the invention is concerned with an injectorconfiguration which can take advantage of the principles of the aboveInternational application, as well as a fuel delivery system using thatinjector.

Accordingly to this aspect of the invention there is provided a fuelinjector for a fuel delivery system for delivering fuel to a cylinder ofa vehicle engine, the injector comprising:

an injector body having an end region which comprises a fuel storagesection in which fuel is stored for ejection from the injector, and anoperating section for operating the injector to eject the fuel from theend region; and

a heating component for substantially continuously heating the endregion of the injector when the injector is in operation supplying fuelto the cylinder, to maintain the end region and therefore the fuel inthe fuel storage section at a temperature so that when the fuel isejected from the injector, the fuel immediately converts to a vapourstate because of the elevated temperature of the fuel and the change inpressure experienced by the fuel when the fuel leaves the injector.

In the preferred embodiment of this aspect of the invention, the heatingcomponent comprises an enlarged end region of the injector which isdimensioned so that when the injector is inserted into an injector portof the vehicle engine, the enlarged end region is in thermal contactwith a wall defining the injector port so that heat is transferred fromthe engine by direct conduction to the enlarged end region of theinjector, and therefore to the fuel in the fuel storage section.

In other embodiments, the heating component could take other forms suchas an electric form or heat by way of exhaust gas, provided that theheating is substantially constant so that the injector is continuouslyheated when the engine is operating, as distinct from heated only oninitial start-up of the engine for overcoming problems with coldstarting of the engine.

This aspect of the invention may also be said to reside in a fueldelivery system for a vehicle engine which includes a cylinder and aninjector port having a wall, the fuel delivery system comprising:

an injector having an ejector body which is formed with an end regionwhich comprises a fuel storage section in which fuel is stored forejection from the injector, and an operating section for operating theinjector to eject the fuel from the end region; and

the end region of the injector having a dimension so that at least partof the end region of the injector body makes thermal contact with thewall of the injector port so that during operation of the vehicleengine, heat is conducted from the engine via the wall of the injectorport to the enlarged portion of the injector to thereby heat fuel in thefuel storage section so that when fuel is ejected from the injector, thefuel immediately converts to a vapour state because of the elevatedtemperature of the fuel and the change in pressure experienced by thefuel when the fuel leaves the injector.

Preferably the end region has an outer wall and the end region isdimensional so that substantially all of the outer wall contacts thewall of the injector port.

In the preferred embodiment of the invention, the end region issubstantially cylinder or disc shape, and has an outer wall whichcontacts substantially the entirety of the wall of the injector port.

Preferably the end region includes a seal for sealing the end region inthe injector port.

A further aspect of the invention provides an injector which has beendesigned to enable easy implementation of the first aspect of theinvention.

Thus, the further aspect of the invention provides an injector for afuel delivery system for delivering fuel to a cylinder of an engine, theengine having an injector port for receiving the injector, said injectorcomprising:

an injector body;

an end region extending from the injector body for storing fuel to beejected from the injector, the end region having a first end from whichthe fuel is ejected, and a second end;

the end region having a dimension so that when the end region is locatedin the injector port, a heating chamber is formed between the end regionof the injector and a wall of the injector port;

the first end of the injector being free of any seal so exhaust gas canmove past the first end and into the chamber when the injector islocated in the injector port and the engine is operating; and

a seal adjacent the second end of the end region for sealing theinjector in the injector port.

Preferably the seal is formed by a shoulder located at the second endand which forms a transition between the end region and the injectorbody so that the shoulder can seat on part of an outer wall of theengine in which the injector port is formed.

Preferably the shoulder is a tapered annular wall for seating on a partof the outer wall of the engine at the periphery of the injector port.

BRIEF DESCRIPTION OF THE DRAWINGS

A preferred embodiment of the invention will be described, by way ofexample, with reference to the accompanying drawings in which:

FIG. 1 is a view of a standard arrangement of a direct injection system;

FIG. 2 is a view according to a first embodiment of the invention;

FIG. 3A is a view of a collar according to one embodiment of theinvention;

FIG. 3B is a cross-sectional view through the collar of FIG. 3A;

FIG. 3C is a side view of the collar of FIG. 3A;

FIG. 4A is a plan view of a collar according to a further embodiment;

FIG. 4B is a cross-sectional view of the collar of FIG. 4A;

FIG. 4C is a side view of the collar of FIG. 4A;

FIG. 5 is a view of a further embodiment of the invention;

FIG. 6 is a view of a still further embodiment of the invention;

FIGS. 7 and 7A are a plan view and cross-sectional view of a sealingelement used in the embodiment of FIG. 5;

FIG. 8 and FIG. 8A are a plan view and cross-sectional view of a sealingelement used in the embodiment of FIG. 6;

FIG. 9 and FIG. 9A are a plan view and cross-sectional view of a collaraccording to a still further embodiment;

FIG. 10 is a view of a prior art injector to illustrate the differencesbetween such an injector and an injector according to a furtherembodiment of the invention;

FIG. 11 is a cross-sectional view of an injector according to thefurther embodiment of the invention;

FIG. 12 is a view of the injector of FIG. 11 fitted into an engine;

FIG. 13 is a view of a standard direct injection-type injector which canbe used with diesel engines; and

FIG. 14 is a view of a modified injector according to yet anotherembodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows a standard direct injection system for a diesel engine inwhich a head 10 of the engine includes an inlet port 12, an exhaust port14 and a combustion chamber 16. A bore 18 which forms an injector portis provided in the head 10 and has an inwardly directed flange 20 at itsinner end. A fuel injector 21 is located in the bore 18 and rests on theflange 20 so as to seal the end of the bore 18.

Fuel is supplied to the injector 18 via supply 22 so the fuel can beejected from the injector 21 into the chamber 16.

FIG. 2 shows the first embodiment of the present invention. Likereference numerals indicate like parts to those described with referenceto FIG. 1.

FIG. 2 also shows the engine block 30 and a piston 32 within thecombustion chamber 16. It should be noted that the head 10 is separatedfrom the block 30, but obviously sits on the block 30 and is secured tothe block 30 in the conventional manner.

Injector 21 is located in the bore 18 in the same manner as describedwith reference to FIG. 1, except that in this embodiment, the end 23 ofthe bore 18 which communicates with the combustion chamber 16 is open.In the preferred embodiment, in order to ensure that the end 23 is open,a spacer collar 25 is located in the bore 18 and sits on the flange 20.The spacer collar 25 therefore allows fluid communication between thecombustion chamber 16 and a heating chamber 40 which is defined betweenthe bore wall 18 a, the injector 21 and the closed or sealed end 42 ofthe bore 18 which is remote from the end 23.

In the embodiment shown in FIG. 2, the collar 25 is provided with aplurality of holes 27 which pass through the side wall of the collar tofacilitate the flow of gas in the chamber 16 into the heating chamber 40and allows the extraction of gas from the heating chamber 40 back intothe chamber 16.

The spacer collar 25 also serves to lift the injector 21 within the bore18 from the position it would normally occupy, as is shown in FIG. 1, toensure that the electric section 21 a of the injector 21 is outside thebore which is defined between the sealed end 42 and the end 23. In otherwords, the body of the injector 21 in which the electric components foroperating the injector, and which are shown by reference 21 a, isexterior of the heating chamber 40. The injector 21 has an electricconnector 21 c for supplying power to the injector. The portion 21 b ofthe injector 21 in which the fuel is stored, and which is the end regionof the injector, is the part of the injector which, together with thebore wall 18 a and the sealed end 42, define the heating chamber 40. Theinjector 21 may also have a tip in the form of a projecting tip 29 fromwhich the fuel is ejected. The tip 29 is adjacent the end 23 so thatfuel is directly injected into the combustion chamber 16.

As is known in diesel engines, the fuel which is ejected into the engineis ignited by compression of gases within the chamber 16 during thecompression stroke of the piston 32. That is, as the piston 32 rises inthe chamber after the collection of intake air through the inlet 12, thepressure of the air increases thereby heating the air to a sufficienttemperature to cause combustion of the fuel and air mixture within thecombustion chamber 16. However, as the piston rises on its compressionstroke and compresses the air within the chamber 16, the air is alsopushed through the open end 23 into the heating chamber 40 so that thehot compressed air created by each compression stroke heats the endregion or fuel storage section 21 b of the injector 21, therebyelevating the temperature of the fuel stored in that section of theinjector. The result of this, as is explained in detail in our aforesaidInternational application, is that the fuel in the end region 21 b isheated to such an extent that as soon as it is ejected from the injector21, the fuel immediately converts to a vapour state because of theelevated temperature of the fuel and the change in pressure experiencedby the fuel when the fuel leaves the injector 21. Thus, the fuel is inan ideal state for combustion within the chamber 16, thereby providingthe fuel economy and other advantages which are described in detail inour aforesaid International application.

During the operating cycle of the engine, air is drawn through the inletport 12 during the suction stroke of the piston 32. The air is thencompressed by the compression stroke of the piston, and when the pistonapproaches top dead centre, fuel is ejected from the injector 21. Thecompression of the air in the compression stroke therefore elevates thetemperature of the vaporised fuel so as to cause ignition. Because theair has been substantially wholly compressed prior to ejection of thefuel from the injector 21, substantially none of the fuel vapour entersthe heating chamber 18. Furthermore, because the fuel leaves theinjector and immediately converts to vapour, all of the ejected fuel isavailable for combustion, thereby greatly improving efficiency.

In the embodiment of FIG. 2, the end 42 of the bore 18 is sealed by anO-ring type seal 50. The O-ring may be held in place by a suitable plate(not shown) or other device if necessary.

FIG. 5 shows a further embodiment in which like reference numeralsindicate like parts to those previously described. In this embodiment,the collar 25 is of the type shown in FIGS. 4A, 4B and 4C. As shown inFIG. 4A, the collar is an annular ring and slots 51 (see FIG. 4C) arecut into the side wall of the annular ring 25 to provide a passagethrough which the compressed gases within the chamber 16 can pass intothe heating chamber 40. In this embodiment, the end 42 is sealed by agenerally annular seal plate 60 of the type shown in FIGS. 7 and 7A. Theplate 60 is annular in configuration and has two lugs 61 which arediametrically opposed and provided with holes 63 for enabling a bolt 70to pass through the holes and through a flange 21 c on the fuel injector21 so as to secure the injector 21 to the head 10 and also seal the endof the heating chamber 40.

In FIG. 6 the collar 25 is of the type shown in FIGS. 3A, 3B and 3C inwhich the holes 27 previously described are provided in the side wall ofthe collar 25 to facilitate the passage of compressed gas between theheating chamber 40 and the combustion chamber 16.

In this embodiment, the sealing plate 42 is similar in plan view to thatshown in FIG. 7, as is illustrated in FIG. 8. However, incross-sectional view shown in FIG. 8A, the plate 42 has an innerdownwardly projecting wall 65 which has a tapered outer end 67 whichlocates within the bore 18. Again, the plate 42 is secured in place bybolts 70 which pass through the holes 63 and screw into the head 10.

FIG. 9 shows a still further embodiment in which the seal is in the formof an O-ring of the type shown in FIG. 2.

FIGS. 10 to 12 show a further embodiment of the invention. FIG. 10 is aview of a conventional injector typical of those used in petrol orgasoline type engines, and which locate in an injector port 100 (seeFIG. 12) of an inlet manifold 101 a of a vehicle engine 101.

The injector of FIG. 10 includes an end region 110 and an operatingsection 111 in which the electronic operating components such as a coil,pintle and the like are housed for operating the injector 111 so thatthe pintle can be moved away from a seat in the end region 110 to enablefuel to be ejected from the injector under the control of a vehiclemanagement system (not shown) which supplies electrical signals to theinjector in a manner which is well known.

In conventional systems, the end region 110 locates in the injector port100 and is isolated from the wall 114 of the injector port by spacers orO-rings. This is done specifically to maintain the injector end regionrelatively cool, and therefore to maintain the fuel in the injector endregion 110 also relatively cool. Thus, in the conventional system, heatis not conducted from the injector port wall 114 to the end region 110of a conventional injector.

The injector shown in FIG. 11 and according to the preferred embodimentof this aspect of the invention, is the same as the injector shown inFIG. 10, except that the end region 110′ is enlarged and configured sothat it will make thermal contact with wall 114 of the port 100. Thus,the heat of the engine is conducted from the wall 114 to the end region110′, and therefore to the fuel storage section shown schematically at115 in FIG. 12. Thus, the fuel is heated to an elevated temperature sothat when the fuel is ejected from the injector, the fuel immediatelyconverts to vapour because of the elevated temperature of the fuel, andthe change in pressure experienced by the fuel when the fuel leaves theinjector. Thus, the fuel is in an ideal state for combustion within thechamber 101 b as previously described.

In the preferred embodiment of the invention, the enlarged end region110′ is preferably generally cylinder or disc shape in configuration.However, other shapes are possible depending on the shape of theinjector port 100 and consistent with the concept of providing directconduction of heat from the engine 101 to the end region 110′ to heatthe fuel in the manner described above.

The end region 110 is generally in the form of a solid metal end regionor other conducting material and, as is apparent from the foregoingdescription, is an integral part of the end region of the injector.Thus, the end region 110 has an outer wall 118 and the enlarged endregion 110 is solid material through to the chamber 115. Thus, heat isreadily conducted from the wall 114 of the injector port 100 to the wall118 of the end region 110′ to the fuel in the storage section 115.

Thus, it will be apparent that during operation of the invention, theend region 110′ is continuously heated so as to maintain the fuel in thestorage 115 at the elevated temperature substantially at all timesduring operation of the engine.

Accordingly, no modification or interference with the standard size ofthe engine inlet port 100 needs to occur, and the injector itself isdimensioned so that it will fit and make thermal contact with theinjector port to provide the heat transfer. Thus, the inlet port 100 canbe left standard without any modification and, furthermore, the injectoritself includes all of the features in order to effect heat transfer tothe fuel in the injector. Thus, the amount of parts is minimised and,indeed, the amount of parts is no greater than in a standard fuelinjector system in which the injector is spaced from the port 100.

In initial engine start-up when the engine is starting from cold, theenlarged end region 110′ may also include an electrical heater to heatthe end region more quickly to the elevated temperature until such timeas the engine is warm enough so as to maintain the end region 110′ andtherefore the fuel at the elevated temperature, by way of conduction ofheat from the engine via the wall 114 of the port 100. The electricalheating element in this embodiment of the invention would beincorporated into the end region 110′ and would operate generally asdescribed in our co-pending International Application No. PCT/AU03/01156(the contents of which are incorporated into this specification by thisreference). In accordance with the teachings of that Internationalapplication, the electrical heating is switched off when the temperatureis elevated to the required temperature, but may again switch on if, forany reason during operation of the engine, the end region 110′ dropsbelow the required temperature.

As is apparent from FIG. 12, the operating section 111 of the injectoris maintained in a relatively cooler environment, and therefore theheating of the end region 110′ by the direct conduction of heat from thewall 114 does not overheat the operating section 111, which would causefailure of the electronic componentry in the operating section 111.

In one embodiment of the invention, the end region 110′ may include agroove 120 as is shown in FIG. 11, for containing an O-ring 121 tofacilitate sealing of the enlarged end region 110′ in the injector port100.

FIG. 13 is a view of a conventional injector used for injecting fueldirectly into a cylinder of an engine. As is well known, this injectorincludes a body in which the operating components are located and an endregion 130 which locates in injector port 18. The injector is sealed inthe port by a seal 142 to prevent exhaust gases from moving into theinjector port.

As has been made clear in relation to the embodiments of FIGS. 1 to 9A,the end of the port corresponding to the seal 142 in the conventionalsystem described above is left open so exhaust gases can move into theinjector port to heat the end region 130.

FIG. 14 is a view of a modified injector, particularly for dieselengines (which could also be used for petrol engines) according toanother embodiment of the invention which enables the concept of FIGS. 1to 9A to be more easily implemented.

In the embodiment of FIG. 14, the injector has a body 132′ in which theoperating components are located, and an end region 130′ which isslightly narrower than in the injector of FIG. 13, and a shoulder 131 isprovided which can seat on the outer wall 133 of the cylinder head 10 toseal the injector port 18. The shoulder 131 is formed at a second end ofthe end region 130 remote from the end 29 from which the fuel isejected. The shoulder 131 is in the form of an annular wall which seatson a part of the outer wall 133 of the cylinder head 10 at the peripheryof the injector 18. The shoulder 131 can be metal or could be providedwith a sealing gasket-type material so as to form an effective seal withthe periphery of the port 140 at the wall 133. The inner end 135 of theinjector port 18 is left open so exhaust gases can move into the port 18and into the chamber 40 to surround the end region 130′ to heat the endregion, as described with reference to FIGS. 1 to 9A. The seal formed bythe shoulder 131 seating on the wall 133 of the cylinder head 10prevents the exhaust gases from escaping passed the injector in FIG. 14through the port 18 to atmosphere.

Since modifications within the spirit and scope of the invention mayreadily be effected by persons skilled within the art, it is to beunderstood that this invention is not limited to the particularembodiment described by way of example hereinabove.

In the claims which follow and in the preceding description of theinvention, except where the context requires otherwise due to expresslanguage or necessary implication, the word “comprise”, or variationssuch as “comprises” or “comprising”, is used in an inclusive sense, i.e.to specify the presence of the stated features but not to preclude thepresence or addition of further features in various embodiments of theinvention.

1. A diesel engine fuel delivery system for an engine which has acombustion chamber, a piston moveable in the combustion chamber, an airinlet port and an exhaust port, comprising: a bore in the engine havinga first open end communicating with the combustion chamber, and a secondend remote from the first end, the bore having a bore wall; a fuelinjector located in the bore and having an injection tip adjacent thefirst end for direct injection of fuel into the combustion chamber, theinjector having a fuel storage section in which fuel is stored forejection from the injector and an operating section for operating theinjector to eject the fuel from the tip of the injector; the second endof the bore being closed; a heating chamber defined by the bore wall,the closed second end of the bore and the injector; the injector beinglocated in the bore so that the fuel storage section is within theheating chamber; and wherein during a compression stroke of the pistongas within the combustion chamber is compressed and forced through thefirst open end of the bore into the chamber to heat the fuel storagesection of the injector so as to raise the temperature of the fuel inthe fuel storage section so that as soon as the fuel leaves theinjector, the fuel substantially immediately converts to vapour statebecause of the heating of the fuel and the change in pressureexperienced by the fuel when the fuel leaves the injector and enters thechamber.
 2. The system of claim 1 wherein the injector has a mechanicaloperating section which is operated by fuel pressure.
 3. The system ofclaim 1 wherein the injector has an electric operating section, theelectric operating section being exterior of the chamber to prevent theheating within the chamber from destroying the electric operatingsection of the injector.
 4. The system of claim 1 wherein the bore hasan inwardly directed flange and a collar located on the flange forreceiving an end of the injector so as to raise the injector slightly inthe bore and to provide a passage through which the gases compressed inthe cylinder can pass into the heating chamber.
 5. The system of claim 4wherein the second end of the bore is closed by a sealing element. 6.The system of claim 5 wherein the sealing element is a shoulder formedon the injector remote from the tip for sealing the second end of thebore.
 7. The system of claim 4 wherein the collar has a generallyannular ring and has apertures or holes to facilitate the passage of gasfrom the combustion chamber into the heating chamber, and from theheating chamber back into the combustion chamber.
 8. A fuel injector fora fuel delivery system for delivering fuel to a cylinder of a vehicleengine, the injector comprising: an injector body having an end regionwhich comprises a fuel storage section in which fuel is stored forejection from the injector, and an operating section for operating theinjector to eject the fuel from the end region; and a heating componentfor substantially continuously heating the end region of the injectorwhen the injector is in operation supplying fuel to the cylinder, tomaintain the end region and therefore the fuel in the fuel storagesection at a temperature so that when the fuel is ejected from theinjector, the fuel immediately converts to a vapour state because of theelevated temperature of the fuel and the change in pressure experiencedby the fuel when the fuel leaves the injector, and wherein the heatingcomponent comprises a portion of the injector adjacent the end regionfor making contact with a wall of an injector port so that heat isdirectly conducted from the vehicle engine to the injector.
 9. Theinjector of claim 8 wherein the heating component comprises an enlargedend region of the injector which is dimensioned so that when theinjector is inserted into an injector port of the vehicle engine, theenlarged end region is in thermal contact with a wall defining theinjector port so that heat is transferred from the engine by directconduction to the enlarged end region of the injector, and therefore tothe fuel in the fuel storage section.
 10. A fuel delivery system for avehicle engine which includes a cylinder and an injector port having awall, the fuel delivery system comprising: an injector having an ejectorbody which is formed with an end region which comprises a fuel storagesection in which fuel is stored for ejection from the injector, and anoperating section for operating the injector to eject the fuel from theend region; and the end region of the injector having a dimension sothat at least part of the end region of the injector body makes thermalcontact with the wall of the injector port so that during operation ofthe vehicle engine, heat is conducted from the engine via the wall ofthe injector port to the enlarged portion of the injector to therebyheat fuel in the fuel storage section so that when fuel is ejected fromthe injector, the fuel immediately converts to a vapour state because ofthe elevated temperature of the fuel and the change in pressureexperienced by the fuel when the fuel leaves the injector.
 11. Thesystem of claim 10 wherein the end region has an outer wall and the endregion is dimensional so that substantially all of the outer wallcontacts the wall of the injector port.
 12. The system of claim 11wherein the end region is substantially cylinder or disc shape, and hasan outer wall which contacts substantially the entirety of the wall ofthe injector port.
 13. The system of claim 10 wherein the end regionincludes a seal for sealing the end region in the injector port.
 14. Aninjector for a fuel delivery system for delivering fuel to a cylinder ofan engine, the engine having an injector port for receiving theinjector, said injector comprising: an injector body; an end regionextending from the injector body for storing fuel to be ejected from theinjector, the end region having a first end from which the fuel isejected, and a second end; the end region having a dimension so thatwhen the end region is located in the injector port, a heating chamberis formed between the end region of the injector and a wall of theinjector port; the first end of the injector being free of any seal soexhaust gas can move past the first end and into the chamber when theinjector is located in the injector port and the engine is operating;and a seal adjacent the second end of the end region for sealing theinjector in the injector port.
 15. The injector of claim 14 wherein theseal is formed by a shoulder located at the second end and which forms atransition between the end region and the injector body so that theshoulder can seat on part of an outer wall of the engine in which theinjector port is formed.
 16. The injector of claim 15 wherein theshoulder is a tapered annular wall for seating on a part of the outerwall of the engine at the periphery of the injector port.